Political Polarization Takes Hold of the Supreme Court

WASHINGTON — As President Trump prepares to name a new justice, one reality is increasingly clear about the Supreme Court — it has become another polarized institution in the polarized capital of a polarized nation.

The string of politically charged 5-to-4 decisions that punctuated the end of the court’s term highlighted how thoroughly the tribal politics that have engulfed the White House and Capitol Hill have now ensnared the court. In deciding major cases with clear political overtones, an extremely reliable indicator of what side a justice would come down on was whether he or she was appointed by a president with an “R” or a “D” behind his name.

“It is clearly the most partisan court ever, where you can actually look at Republican and Democrat and use that as a proxy for voting and behavior on the court,” said Neal E. Devins, the Sandra Day O’Connor professor of law at the College of William and Mary, who has studied the partisan evolution of the court.

And this is before Mr. Trump’s virtually certain nomination of another conservative, a development expected to make the partisan divide even more stark. With one recent poll showing that half of American voters believe the Supreme Court is driven mainly by politics, lawmakers in both parties worry that the perception is destroying trust in the court as a supposed neutral arbiter of the United States’ political and policy disputes.

“People expect that the executive and legislative branches are going to be political, but the judiciary is supposed to be above the fray,” said Senator Susan Collins, Republican of Maine, whose vote is likely to be pivotal in the coming confirmation fight. “But when you talk about ideological blocs on the court, then you are eroding the public’s faith in the judicial system and the rule of law, and I think that is really serious.”

Senator Patrick J. Leahy, Democrat of Vermont and a longtime senior member of the Judiciary Committee, said the rising partisanship of the judiciary presents a major obstacle for the Supreme Court if it comes to be viewed mainly as a creature of politics.

John G. Roberts Jr., the chief justice being referred to by Mr. Leahy and a man appointed by President George W. Bush, seems to understand that.

He has given multiple speeches lamenting the jaded view that many Americans have developed toward the court as well as toward the highly political tone of the confirmation process. He has tried to educate the public on the distinction between judges confirmed to determine the constitutionality of policy rather than the wisdom of the underlying policy itself. Demonstrating the difference, he joined justices appointed by Democratic presidents in upholding the Affordable Care Act.

But polishing the reputation of the court for its independence can be very difficult when the most notable decisions are being decided mainly along partisan lines and when political reliability has become a chief attribute presidents look for in making their Supreme Court picks.

Mr. Trump has not helped efforts by Chief Justice Roberts to tone down the political atmosphere surrounding the court. Back in March, the president tried to whip up voters for 2018 by saying that Congress needed more Republicans and that his party “must ALWAYS hold the Supreme Court,” treating it as if it was just another branch of the legislature. His tweet no doubt caused some discomfort for Chief Justice Roberts and others who pride themselves on the tradition of judicial independence, but it also represented exactly how many Americans view the courts.

Mr. Devins, the law professor, said the difference between the current court and those in the past was that there was typically either a conservative appointed by a Democratic president or a liberal named by a Republican. And past presidents sometimes dipped into their own circle of advisers and allies to fill a court seat, heightening the personal relationship over the political in making the choice. Those days seem long gone.

“The parties now seek political advantage by demonstrating on that issue they are not like the other party,” he said of the nomination process. “It is in their best interest to show their constituents they are for a different kind of judge.”

Mr. Devins noted that the Supreme Court hasn’t fully descended to the level of partisanship of Congress, as shown by the recent ruling siding with a Colorado baker who refused to prepare a wedding cake for a gay couple. Sidestepping the central issue, the seven-justice majority included two members of the court’s liberal wing. In many of the court’s decisions on more mundane and technical questions, there is often a broader consensus.

But in the highly political cases that closed the session on labor, voting rights and the travel ban, among others, the partisan divide was unmistakable, highlighted by the tough tone of dissenting opinions in which justices appointed by Democrats torched the Republican-appointed majority for what they portrayed as badly misguided and political rulings.

The coming confirmation hearings promise to represent another escalation in the partisanship enveloping the court. The hearings will be to replace Justice Kennedy, the last member of the court to be seated with a unanimous Senate vote. It is unlikely there will be another such vote anytime soon.

A version of this article appears in print on , on Page A11 of the New York edition with the headline: Political Polarization Takes Hold of the Supreme Court. Order Reprints | Today’s Paper | Subscribe